JP7364042B2 - Battery packs and power tools - Google Patents

Description

The present invention relates to a battery pack and a power tool.

BACKGROUND ART A battery pack, in which a battery cell group in which a plurality of battery cells such as lithium ion secondary battery cells are electrically connected is housed in an exterior case, is widely used in electric vehicles, power tools, and the like. If moisture enters the inside of the battery pack, it may cause damage to the battery cells. Therefore, battery packs are required to have improved waterproof properties.

In Patent Document 1 listed below, a double-sided tape that covers the electrode surface of a battery pack is pasted, a metal plate (lead plate or tab plate) is pasted on the double-sided tape, and the battery electrode surface and its surroundings are pasted on the metal plate. A structure has been proposed in which a waterproof resin layer covering the surrounding area is provided.

In Patent Document 2 listed below, an elastic body having an opening is arranged between a battery positive electrode part and a battery holder (exterior case) opening, and a predetermined part of the elastic body is sandwiched between an end surface near the battery positive electrode part and the inner surface of the holder. A structure has been proposed in which a certain portion of the elastic body exposed from the opening of the battery holder is sandwiched between the battery positive electrode part and the lead plate.

JP2012-45121A JP2013-73864A

Since the techniques proposed in Patent Documents 1 and 2 require new parts and configurations, there is room for improvement from the viewpoint of regulating the addition of parts. Furthermore, there is room for improvement in the techniques proposed in Patent Documents 1 and 2 from the viewpoint of avoiding a decrease in waterproofness when a new component is out of stock or when the installation position of a new component is shifted.

One of the objects of the present invention is to improve the waterproofness of a battery pack without adding new members or structures.

The present invention
exterior case,
A cylindrical battery cell having a positive terminal at one end and a negative terminal at the other end;
a metal plate connected to the positive terminal part or the negative terminal part,
The battery cell has a peripheral convex portion around the positive electrode terminal portion or the negative electrode terminal portion,
The metal plate has a convex portion facing the peripheral convex portion,
The convex portion is a battery pack disposed in close contact with the entire circumference of the peripheral convex portion via a first insulating portion.
Further, the battery pack of the present invention may be included in a power tool.

According to the present invention, the waterproofness of a battery pack can be improved without adding new members or structures.

FIG. 1 is an exploded perspective view for explaining a battery pack according to a first embodiment. FIG. 2 is a perspective view for explaining the exterior case of the battery pack. FIG. 3 is a block diagram showing an example of the configuration of the battery holder according to the first embodiment. FIG. 4 is a perspective view showing an example of a metal plate. FIG. 5A is a schematic cross-sectional view showing an example of the arrangement of battery cells and metal plates. FIG. 5B is an enlarged cross-sectional view showing a region S surrounded by a broken line in FIG. 5A. FIG. 6 is a schematic cross-sectional view showing an example of a state in which a metal plate and a battery cell are joined. FIGS. 7A and 7B are perspective views showing an example of a case where a thin portion is formed in a metal plate. FIG. 8 is a schematic cross-sectional view showing an example of the arrangement of battery cells and the metal plate shown in FIG. 7A. FIG. 9A is a perspective view showing an example of a case where a second insulating section is provided on a metal plate. FIG. 9B is a schematic cross-sectional view showing an example of the arrangement of battery cells and the metal plate shown in FIG. 9A. FIG. 10 is a schematic cross-sectional view showing a structural example of a battery cell. FIG. 11 is a diagram for explaining an application example of the battery pack.

Embodiments of the present invention will be described in the following order.
1. Battery pack according to the first embodiment 2. Battery pack according to the second embodiment 3. Application example 4. Modifications Note that the present invention is not limited to the embodiments described below. In the following description, directions such as front and back, left and right, and up and down are shown for convenience of explanation, but the content of the present invention is not limited to these directions.

[1. Battery pack according to the first embodiment]
A specific example and a preferred example of the battery pack (battery pack 1) according to the first embodiment will be described with reference to FIGS. 1 to 10. FIG. 1 is an exploded perspective view for explaining a configuration example of a battery pack 1. As shown in FIG. FIG. 2 is a perspective view for explaining the appearance of the battery pack 1. The battery pack 1 according to the first embodiment includes, for example, an outer case 2, a circuit board 3, a battery cell 4, and a metal plate 5, as shown in FIGS. 1, 2, etc. A circuit board 3, a battery cell 4, and a metal plate 5 are housed inside.

(Exterior case)
As shown in FIGS. 1 and 2, the exterior case 2 includes an upper case 2a and a lower case 2b. The outer case 2 is formed by engaging and integrating the upper case 2a and the lower case 2b. In the example shown in FIGS. 1 and 2, the upper case 2a has a substantially rectangular upper surface plate 6. As shown in FIG. From the entire outer edge of the top plate 6, a side plate 7 is erected downward (in the −Z direction in FIG. 1). Side plates 7 are provided upright from each of the four sides of the top plate 6. The depth of the upper case 2a is not particularly limited, but in the examples shown in FIGS. 1 and 2, it is formed shallower than the depth of the lower case 2b.

The lower case 2b has a substantially rectangular bottom plate 8. A side plate 9 is erected upward (in the +Z direction in FIG. 1) from the entire outer edge of the bottom plate 8. Side plates 9 are provided upright from each of the four sides of the bottom plate 8. External connection terminals 30 are provided on predetermined side plates 9 .

A hole 10 for screw tightening is formed in each of the upper case 2a and the lower case 2b. A hole 10 of the lower case 2b is formed at a position facing the hole 10 of the upper case 2a. In the example of FIG. 1, holes 10 are formed at the four corners of the upper case 2a and the lower case 2b, and the outer case 2 also has holes 10 formed at the four corners. A screw 11 is inserted into each hole 10 and rotated. The screw 11 passes through the hole 10 of the upper case 2a and reaches the hole 10 of the lower case 2b. Furthermore, by rotating each screw 11, the screws are tightened, and the upper case 2a and the lower case 2b are fixed.

(Battery holder)
A battery holder 12 is housed in the interior space of the exterior case 2. As shown in FIG. 3, a plurality of battery cell storage sections 13 are formed in the battery holder 12. As shown in FIG. The battery cell storage portion 13 is, for example, formed in a cylindrical shape. The axial direction of the battery cell housing section 13 is the left-right direction (Y direction) when the battery holder 12 is housed in the exterior case 2. Ends of the battery cell storage portion 13 facing each other along the axial direction are opened in, for example, a substantially circular shape.

Moreover, in the battery holder 12, each battery cell storage part 13 is formed along with the up-down direction (Z direction) and the front-back direction (X direction). In the example shown in FIGS. 1 and 2, the battery cell storage sections 13 are arranged in four rows in the front-back direction and two rows in the vertical direction, and battery cells 4 are stored in each row. Note that this is just an example, and the number of rows in the front-rear direction and the number of rows in the vertical direction of the battery cell storage portion 13 are not limited to the example shown in FIG. 1 and the like. Further, the number of battery cells accommodated in one battery cell storage section 13 is not limited to one either.

As the material of the battery holder 12, for example, an insulating material is suitably used, and specifically, resin such as plastic is used.

(battery cell)
The battery cell 4 is a battery having a cylindrical shape, and for example, a cylindrical lithium ion secondary battery as described below can be employed. The battery cell 4 may be another secondary battery such as a lithium ion polymer secondary battery.

Electrode terminal portions are formed on each of both end surfaces of the battery cell 4. A positive electrode terminal portion 15 is formed as an electrode terminal portion on one end surface of the battery cell 4, and a negative electrode terminal portion 16 is formed as an electrode terminal portion on the other end surface of the battery cell 4. When the battery cell 4 is housed in the battery cell storage section 13, the positive terminal section 15 or the negative terminal section 16 of the battery cell 4 is exposed through an opening formed at an end of the battery cell storage section 13.

Regarding the arrangement of the plurality of battery cells 4 stored in the battery cell storage part 13 of the battery holder 12, as shown in FIG. The electrode terminal portions exposed on the same side are arranged with the same polarity. For example, the positive electrode terminal portion 15 of the battery cell 4 placed on the upper side and the positive electrode terminal portion 15 of the battery cell 4 placed on the lower side are arranged so as to face the same direction. Battery cells 4 adjacent in the front-rear direction (X direction) are arranged with electrode terminal portions exposed on the same side of the battery holder 12 having different polarities. For example, when looking at a combination of a plurality of battery cells 4 housed in the battery holder 12 with the direction (Y direction) from one end surface side to the other end surface side of the battery cells 4 as the viewing direction, the positive electrode terminal portion 15 and The battery cells 4 are arranged so that the negative electrode terminal portions 16 are arranged alternately. Note that the arrangement of the battery cells 4 described above is an example, and is not limited to the arrangement illustrated in FIG. 3 and the like.

(Peripheral protrusion)
As will be described later using FIG. 10, etc., the battery cell 4 is formed in the shape of a battery can with one side open and a battery lid placed on the opening side, and a protruding portion is formed on the center side of the battery lid. , this portion forms the positive electrode terminal portion 15. As shown in the examples of FIGS. 10, 5A, and 5B, a caulking structure of the battery can is formed at the outer circumferential edge of the positive electrode terminal portion 15, and the portion forming this caulking structure touches the peripheral convex portion 21. Eggplant. The peripheral convex portion 21 has a protruding end 32 that protrudes in the same direction as the protruding direction of the positive electrode terminal portion 15, and forms an inclined portion that is curved and inclined in both the inner and outer directions from the protruding end 32. In FIGS. 5A and 5B, reference numeral 33 indicates an outer inclined portion that is curved and inclined outward from the protruding end 32. As shown in FIG. In addition, in FIG. 5A and FIG. 5B, for convenience of explanation, the metal plate 5 and the battery cell 4 are shown in a state where the metal plate 5 is disposed facing the battery cell 4, but the metal plate 5 and the battery cell 4 are not bonded. This also applies to FIGS. 8 and 9B.

(First insulation part)
In the battery cell 4, the outer circumferential surface of a battery can, which will be described later using FIG. A state in which the surface is formed by the first insulating portion 23 is formed. Further, the first insulating portion 23 is provided so as to cover at least the peripheral convex portion 21 . In the examples shown in FIGS. 10, 5A, and 5B, the first insulating portion 23 forms the outer peripheral exposed surface of the battery cell 4, and further covers the peripheral convex portion 21 from the outer peripheral surface of the battery cell 4. It wraps around to the end surface side and extends from the protruding end 32 of the peripheral convex portion 21 toward the positive electrode terminal portion 15 . The extending end of the first insulating portion 23 is located between the positive electrode terminal portion 15 and the peripheral convex portion 21 .

In the battery pack 1, by providing the first insulating portion 23 in this manner, the insulation state between the convex portion 22 of the metal plate 5 and the peripheral convex portion 21 is maintained.

(washer)
The battery cell 4 may further be provided with a washer 31. The washer 31 is an insulating member formed in an annular shape, and is disposed around the outside of the positive electrode terminal portion 15 . As shown in FIG. 5B, the outer circumferential edge of the washer 31 is located at a portion where the circumferential convex portion 21 is formed, and the inner circumferential edge of the washer 31 is located between the positive electrode terminal portion 15 and the circumferential convex portion 21. The positive electrode terminal portion 15 is located closer to the positive electrode terminal portion 15 than the extending end of the first insulating portion 23 .

In the battery pack 1, since the washer 31 is further provided, the insulation state between the convex portion 22 of the metal plate 5 and the peripheral convex portion 21 is maintained more strongly.

(metal plate)
The electrode terminal portions (positive electrode terminal portion 15 and negative electrode terminal portion 16) exposed from the opening of each battery cell storage portion 13 of the battery holder 12 are joined to a metal plate.

In the example shown in FIGS. 1 and 2, one surface of the battery holder 12 is joined to the metal plate 5 and the metal plate 50, and the other surface of the battery holder 12 is joined to the metal plate 5. The metal plate 5 is a positive electrode bonding type metal plate that is bonded to the positive electrode terminal portion 15 to form a terminal contact portion 19 . As the metal plate 5, there are two types: a positive electrode only bonding type metal plate in which only the positive electrode terminal portion 15 is bonded, and a bipolar bonding type metal plate in which the negative electrode terminal portion 16 is also bonded. Regarding the metal plate 5, a metal plate of positive electrode only junction type is sometimes referred to as a first metal plate 5a, and a metal plate of bipolar junction type is sometimes referred to as a second metal plate 5b. The metal plate 50 is a negative electrode only bonding type metal plate in which only the negative electrode terminal portion 16 is bonded.

The first metal plate 5a is located on one surface of the battery holder 12 (the surface on the +Y direction side in FIG. 1) and on the front end side (the direction approaching the external connection terminal 30 when viewed in the front-rear direction (+X direction in FIG. 1)). It is joined to the positive electrode terminal parts 15, 15 exposed from the opening of each vertically adjacent battery cell storage part 13.

The metal plate 50 is attached to the same side as the installation surface of the first metal plate 5a in the battery holder 12, and is attached to the rear end side (the direction away from the external connection terminal 30 when viewed in the front-rear direction (-X in FIG. 1). direction)) is joined to the negative electrode terminal portions 16, 16 exposed from the openings of the respective battery cell housing portions 13 that are vertically adjacent to each other.

Further, a second metal plate 5b located between the first metal plate 5a and the metal plate 50 is attached to the same side of the battery holder 12 as the installation surface of the metal plate 50. This second metal plate 5b has negative electrode terminal portions 16, 16, positive electrode terminal portion 15, and 15.

On the other surface of the battery holder 12 (the opposite surface of the battery holder 12 to the surface on which the metal plate 50 is installed (the surface on the −Y direction side in FIG. 1)), a negative electrode terminal portion 16 is exposed from the opening of the battery cell storage portion 13. and the positive electrode terminal portion 15 are joined by two adjacent second metal plates 5b.

One of the second metal plates 5b is connected to the negative electrode terminal portions 16, 16 exposed from the openings of the two sets of battery cell storage portions 13 on the rear end side among the two pairs of battery cell storage portions 13 adjacent in the vertical direction, and the positive electrode. It is joined to the terminal parts 15, 15.

The other side of the second metal plate 5b is connected to the negative electrode terminal portions 16, 16 exposed from the openings of the two battery cell storage portions 13 on the front end side among the two pairs of battery cell storage portions 13 adjacent in the vertical direction, and the positive electrode terminal. It is joined to the parts 15, 15.

The upper end sides of the first metal plate 5a and the metal plate 50 extend toward the center of the battery holder 12 on the upper surface of the battery holder 12, and the extended portions serve as board connection terminals 18, 18. ing. Board connection terminals 18 and 18 of each of the first metal plate 5a and the metal plate 50 are electrically connected to the circuit board 3 placed on the top surface of the battery holder 12.

The combination and arrangement of the metal plates 5, 50, the shapes of the individual metal plates 5, 50, etc. can be set as appropriate depending on the arrangement of the negative electrode terminal section 16 and the positive electrode terminal section 15, etc.

Preferably, the metal plates 5 and 50 are made of a copper alloy or a similar material. This makes it possible to distribute power with low resistance. The metal plates 5 and 50 are made of, for example, nickel or a nickel alloy. This improves the weldability between the terminal contact portions formed on the metal plates 5 and 50 and the positive terminal portion or the negative terminal portion. The surfaces of the metal plates 5 and 50 may be plated with tin or nickel. This can prevent the surfaces of the metal plates 5 and 50 from oxidizing and rusting.

The battery cells 4 housed in the battery holder 12 are electrically connected to each other by metal plates 5 and 50. In the example shown in FIGS. 1 and 2, two vertically arranged battery cells 4 are connected in a parallel arrangement by metal plates 5, 50, and four sets of two battery cells 4 are arranged in parallel. are electrically connected in series.

(shape of metal plate)
The metal plate 50 has, for example, a flat plate shape, and has two portions in the vertical direction that contact the negative electrode terminal portion 16 when it is joined to the battery cell 4, and a small hole 20 in the center of or near the portion. is formed.

FIG. 4 is a diagram for explaining the external shape of the metal plate 5 when the metal plate 5 is the second metal plate 5b. As shown in FIG. 4, the metal plate 5 has a convex portion 22 around the terminal contact portion 19 that corresponds to the peripheral convex portion 21. In the example shown in FIGS. 1 and 2, a convex portion 22 is provided on a first metal plate 5a and a second metal plate 5b as the metal plate 5. As shown in FIG.

The first metal plate 5a has two portions formed in the vertical direction that become terminal contact portions 19 when joined to the positive electrode terminal portions 15 of the battery cells 4. Further, the second metal plate 5b has a convex portion 22 around the outer periphery of each terminal contact portion 19. The convex portion 22 is formed in a shape corresponding to the peripheral convex portion 21 described later.

As shown in FIG. 4, for example, the second metal plate 5b has two portions (one set) formed in the vertical direction that become the terminal contact portions 19 when joined to the positive terminal portion of the battery cell 4. Further, like the first metal plate 5a, the second metal plate 5b has a convex portion 22 corresponding to the peripheral convex portion 21 on the outer periphery of the portion that will become the terminal contact portion 19.

Further, in the second metal plate 5b, two portions that contact the negative electrode terminal portion 16 are formed in the vertical direction, and a small hole 20 is formed at or near the center of the portion.

(Protrusion)
A convex portion 22 is formed on the metal plate 5 at the outer periphery of a portion that will become the terminal contact portion 19 on the side facing the positive electrode terminal portion 15 . The convex portion 22 is formed in a position and shape corresponding to the peripheral convex portion 21 . In the examples shown in FIGS. 1 and 2, on the main surface of the metal plate 5 that does not face the positive electrode terminal portion 15, the portion corresponding to the convex portion 22 is a concave portion 51. .

In the battery pack 1, as shown in FIGS. 5A and 5B, it is preferable that the convex portion 22 and the peripheral convex portion 21 contact each other outside the protruding end 32 of the peripheral convex portion 21. In this case, in the battery pack 1, by arranging the convex portion 22 and the peripheral convex portion 21 to face each other, it becomes easy to suppress misalignment during positioning of the metal plate 5 with respect to the battery cell 4. A state in which the convex portion 21 is in contact can be more easily formed.

The shape of the convex part 22 is not particularly limited as long as it can be in close contact with the peripheral convex part 21, but as shown in FIGS. 5A, 5B, etc. It is preferable that the outer slope portion 24 is formed in a mountain shape such that the angle P1) is gentler than the slope of the outer slope portion 24 (the slope angle P2 in FIG. 5B) (P1<P2). The inner slope portion 25 refers to a slope portion formed along the surface of the metal plate 5 from a region facing the positive electrode terminal portion 15 toward the outside (in the direction away from the surface) to the position of the top portion 26 of the convex portion 22 . The outer slope portion 24 refers to a slope portion formed from the top portion 26 of the convex portion 22 toward the outside of the metal plate 5 (in the direction away from the region facing the positive electrode terminal portion 15).

When the metal plate 5 forms the convex portion 22 so that P1<P2, the top portion 26 of the convex portion 22 is located outside the protruding end 32 of the peripheral convex portion 21, and the inner slope portion 25 is placed on the peripheral edge. This makes it easier to form a state in which the convex portion 21 is in contact with the outer inclined portion 33, and when positioning the metal plate 5 with respect to the battery cell 4, displacement of the metal plate 5 is less likely to occur. Furthermore, even if the metal plate 5 is slightly misaligned, the state in which any position on the inner slope portion 25 and the outer slope portion 33 of the peripheral edge convex portion 21 are in contact is easily maintained. Therefore, when the metal plate 5 is joined to the battery cell 4, it becomes easy to form a state in which the inner slope portion 25 of the convex portion 22 and the peripheral convex portion 21 are in close contact with each other. When positioning the metal plate 5 with respect to the battery cell 4, as shown in FIGS. The state before formation of the bonded state with the metal plate 5) is shown.

As shown in FIG. 5B, when positioning the metal plate 5 with respect to the battery cell 4, the surface of the main surface of the metal plate 5 that faces the positive electrode terminal portion 15 and the positive electrode terminal portion 15 of the battery cell 4 are aligned. Preferably, a gap is formed between them. That is, when positioning the metal plate 5 with respect to the battery cell 4, the height difference N1 from the main surface of the metal plate 5 to the position of the top part 26 of the convex part 22 and the surface position of the positive electrode terminal part 15 are determined. It is preferable that N1>N2 when compared with the height difference N2 from the top of the convex portion 22 to the position of the top 26. By determining the shape, size, and formation position of the convex portion 22 so that such a gap is formed, when the battery cell 4 and the metal plate 5 are joined, the metal plate 5 is connected to the positive electrode terminal portion 15 of the battery cell 4. Since the terminal contact portion 19 is formed by pressing against the side, a pressing force acts on the contact position between the circumferential edge convex portion 21 and the convex portion 22, and the circumferential edge convex portion 21 and the convex portion 22 can be brought into closer contact with each other. It becomes like this. In addition, at this time, as shown in FIG. 6, the metal plate 5 can be slightly warped outward along the metal plate surface centering on the terminal contact portion 19, making it even stronger. The peripheral convex portion 21 and the convex portion 22 can be brought into close contact. As the metal plate 5 and the positive terminal portion 15 of the battery cell 4 are joined, the peripheral convex portion 21 and the convex portion 22 are brought into close contact, and a waterproof function is achieved.

(Method of joining metal plate and battery cell)
The method of joining the metal plate 5 and the positive electrode terminal portion 15 of the battery cell 4 is not particularly limited, and examples thereof include resistance welding, laser welding, and the like.

(Second insulation part)
In the battery pack 1, it is preferable that a second insulating part 27 is further provided between the convex part 22 and the first insulating part 23, as shown in FIGS. 9A and 9B. Since the battery pack 1 is further provided with the second insulating part 27, even if the first insulating part 23 is damaged, insulation is maintained between the metal plate 5 and the peripheral convex part 21 of the battery cell 4. It is possible to maintain a state in which a member having the following is interposed.

The second insulating portion 27 is not particularly limited, but as shown in FIG. 9A, the second insulating portion 27 is an insulating layer formed on at least a portion of the convex portion 22 by painting or printing. It is. Since the second insulating portion 27 is an insulating layer formed on at least a portion of the convex portion 22 of the metal plate 5, an increase in the number of parts can be suppressed. The material constituting the insulating layer is not particularly limited, but for example, an ultraviolet curable resin having insulating properties can be used. Note that in FIG. 9A, the region where the second insulating portion 27 is formed is shown as a hatched region.

(slit)
In the battery pack 1, as shown in FIG. 4, it is preferable that a slit 28 is provided in a part of the outer periphery of the protrusion 22 of the metal plate 5. Since the slit 28 is provided around the outside of the convex portion 22, when the metal plate 5 is joined to the battery cell 4, warping occurs outward along the metal plate surface centering on the terminal contact portion 19. In this case (see FIG. 6), even if a portion of the metal plate 5 is distorted, the slit 28 can buffer the distortion and prevent the distortion from spreading to the entire metal plate 5. For example, in the example shown in FIG. 4, the slits 28 are provided, so that even if distortion occurs centering on the terminal contact portion 19 when the metal plate 5 is joined to the battery cell 4, the slit 28 buffers the distortion. By doing so, it is possible to prevent distortion centered on the terminal contact portion 19 from spreading to the entire metal plate 5.

The size and position of the slit 28 are not particularly limited as long as the slit 28 is provided in a part of the outer periphery of the convex portion 22 in the metal plate 5; Size, location, etc. The number of slits 28 formed is not particularly limited, and in the example shown in FIG. 4, they are provided at three locations around the outer circumference of one convex portion 22.

(thin part)
As shown in FIGS. 7A, 7B, and 8, the metal plate 5 is preferably provided with a thin portion 29 inside the convex portion 22. In the examples shown in FIGS. 7A and 8 , the thin portion 29 is formed by a groove having a V-shaped cross section and formed along the convex portion 22 . Furthermore, in this example, the grooves are formed on the surface of the main surface of the metal plate 5 that faces the battery cells 4 . Note that the shape of the groove forming the thin portion 29 shown in FIG. 8 is an example, and the shape of the groove is not limited to this.

Since the thin wall portion 29 is provided in the battery pack 1, even if an abnormality occurs in the battery cell 4 and gas blows out from the battery cell 4, the metal plate 5 will not rupture at the thin wall portion 29 due to the pressing force of the gas. By doing so, the gas can easily escape to the outside, and the safety of the battery pack 1 can be improved.

Although the thin portion 29 is formed in a circular shape in FIG. 7A, the shape of the thin portion 29 is not limited to this, and may be formed in a cross shape, for example, as shown in FIG. 7B.

(circuit board)
The circuit board 3 is electrically connected to the external connection terminal 30 of the battery pack 1. In the example of FIG. 1, the circuit board 3 and the external connection terminals 30 are electrically connected via wiring (not shown). The circuit board 3 is electrically connected to the board connection terminal 18 of the metal plate 5, and has an electric circuit mounted thereon. The electric circuit is formed so that power from the battery cell 4 can be supplied to the outside from the external connection terminal 30.

(Example of battery cell)
Here, a specific example of the battery cells 4 accommodated in the battery pack 1 will be further described. An example of the battery cell 4 will be described using a case where the battery cell 4 is a cylindrical lithium ion battery.

FIG. 10 is a schematic cross-sectional view of a lithium ion battery 40 as a battery cell 4. As shown in FIG. The battery cell 4 illustrated in FIG. 10 is a cylindrical lithium ion battery 40 in which an electrode winding body 120 is housed inside a battery can 111.

The lithium ion battery 40 includes a pair of insulators 112 and 113 and an electrode wound body 120 inside a cylindrical battery can 111 . The lithium ion battery 40 may further include one or more of a heat sensitive resistance (PTC) element, a reinforcing member, etc. inside the battery can 111.

(Battery can)
The battery can 111 is a member that mainly houses the electrode winding body 120. This battery can 111 is a cylindrical container with one end open and the other end closed. That is, the battery can 111 has one open end (open end 111N). This battery can 111 contains one or more metal materials such as iron, aluminum, and alloys thereof. However, the surface of the battery can 111 may be plated with one or more metal materials such as nickel.

(Insulator)
The insulators 112 and 113 are sheet-like members having surfaces substantially perpendicular to the winding axis direction of the electrode winding body 120 (vertical direction in FIG. 10). The insulators 112 and 113 are arranged so as to sandwich the electrode winding body 120 between them. As the material of the insulators 112 and 113, polyethylene terephthalate (PET), polypropylene (PP), Bakelite, etc. are used. Bakelite includes paper Bakelite and cloth Bakelite, which are produced by applying phenolic resin to paper or cloth and then heating it.

(Caulked structure)
The battery lid 114 and the safety valve mechanism 130 are crimped to the open end 111N of the battery can 111 via a gasket 115, forming a crimped structure 111R (crimp structure). Thereby, in the state in which the electrode winding body 120 and the like are housed inside the battery can 111, the battery can 111 is sealed.

By forming the caulking structure 111R of the battery can 111, the bent portion 111P is formed to protrude from the battery lid surface position so as to surround the outer periphery of the battery lid 114 when the battery lid 114 is attached to the battery can 111. This bent portion 111P forms the peripheral convex portion 21 described above. The bent portion 111P as the peripheral convex portion 21 is formed in a curved shape, and in the example of FIG. 10, it is formed in a U-shape in cross section.

(Battery cover)
The battery lid 114 is a member that closes the open end 111N of the battery can 111 when the electrode winding body 120 and the like are stored inside the battery can 111, and is made of iron plated with nickel. has been done. This battery lid 114 contains the same material as the material from which the battery can 111 is formed. A protrusion that protrudes in the vertical direction in FIG. 10 is formed in the central region of the battery lid 114.

(Exterior tube)
In the lithium ion battery 40, an insulating exterior tube 153 is provided on the outer peripheral surface of the battery can 111 as the first insulating portion 23 described above. The exterior tube 153 covers the outer peripheral surface of the battery can 111 and the bent portion 111P as the peripheral convex portion 21, and further extends from the bent portion 111P toward the protruding portion of the battery lid 114. The extending end of the exterior tube 153 is located between the protrusion of the battery lid 114 and the caulking structure 111R.

The method for attaching the exterior tube 153 to the battery can 111 is not particularly limited, but for example, the exterior tube 153 may be placed outside the battery can 111 and heated to shrink the exterior tube 153 itself. It can be placed in close contact with the outer periphery of the

(washer)
The lithium ion battery 40 may further be provided with a washer as described above (not shown in FIG. 10). The washer is placed around the outside of the protrusion of the battery lid 114.

(gasket)
The gasket 115 is mainly interposed between the bent portion 111P (also referred to as a crimp portion) of the battery can 111 and the battery lid 114, thereby closing the gap between the bent portion 111P and the battery lid 114. This is a sealing member. The surface of the gasket 115 may be coated with, for example, asphalt.

Gasket 115 includes an insulating material. The type of insulating material is not particularly limited, but may be a polymeric material such as polybutylene terephthalate (PBT) or polypropylene (PP). This is because the gap between the bent portion 111P forming the peripheral convex portion 21 and the battery lid 114 is sufficiently sealed while electrically separating the battery can 111 and the battery lid 114 from each other.

(Safety valve mechanism)
The safety valve mechanism 130 mainly releases the internal pressure by releasing the sealed state of the battery can 111 as necessary when the internal pressure (internal pressure) of the battery can 111 increases. The cause of the increase in the internal pressure of the battery can 111 is gas generated due to a decomposition reaction of the electrolytic solution during charging and discharging.

Of the safety valve mechanism 130, the safety cover 131 is a substantially circular plate-like member, and is also called a valve body. The safety cover 131 is made of aluminum, for example. As shown in FIG. 1, the safety cover 131 may have a protrusion in the center thereof that protrudes toward the electrode winding body 120.

(Electrode wound body)
In a cylindrical lithium ion battery, a strip-shaped positive electrode 121 and a strip-shaped negative electrode 122 are spirally wound with a separator 123 in between, and are housed in a battery can 111 in a state impregnated with an electrolyte. Although not shown, the positive electrode 121 and the negative electrode 122 each have a positive electrode active material layer and a negative electrode active material layer formed on one or both sides of a positive electrode current collector and a negative electrode current collector, respectively. The material of the positive electrode current collector is a metal foil containing aluminum or an aluminum alloy. The material of the negative electrode current collector is a metal foil containing nickel, nickel alloy, copper, or copper alloy. The separator 123 is a porous, insulating film that electrically insulates the positive electrode 121 and negative electrode 122 while allowing the movement of lithium ions.

As shown in FIG. 10, a space (center space 120C) created when winding the positive electrode 121, negative electrode 122, and separator 123 is provided at the center of the electrode winding body 120. , a center pin 124 is inserted. However, the center pin 124 can be omitted.

A positive electrode lead 125 is connected to the positive electrode 121, and a negative electrode lead 126 is connected to the negative electrode 122 (see FIG. 10). The positive electrode lead 125 contains a conductive material such as aluminum. Positive electrode lead 125 is electrically connected to battery lid 114 via safety valve mechanism 130 . Negative electrode lead 126 contains a conductive material such as nickel. Negative electrode lead 126 is electrically connected to battery can 111 . The detailed configuration and materials of each of the positive electrode 121, negative electrode 122, separator 123, and electrolyte will be described later.

(positive electrode)
The positive electrode active material layer includes at least a positive electrode material (positive electrode active material) capable of intercalating and deintercalating lithium, and may further include a positive electrode binder, a positive electrode conductive agent, and the like. The positive electrode material is preferably a lithium-containing composite oxide or a lithium-containing phosphoric acid compound. The lithium-containing composite oxide has, for example, a layered rock salt type or spinel type crystal structure. The lithium-containing phosphoric acid compound has, for example, an olivine crystal structure.

The positive electrode binder contains synthetic rubber or a polymer compound. Synthetic rubbers include styrene-butadiene rubber, fluorine-based rubber, and ethylene propylene diene. Examples of the high molecular compound include polyvinylidene fluoride (PVdF) and polyimide.

The positive electrode conductive agent is a carbon material such as graphite, carbon black, acetylene black, or Ketjen black. However, the positive electrode conductive agent may be a metal material or a conductive polymer.

(Negative electrode)
The surface of the negative electrode current collector is preferably roughened to improve adhesion to the negative electrode active material layer. The negative electrode active material layer includes at least a negative electrode material (negative electrode active material) capable of intercalating and deintercalating lithium, and may further include a negative electrode binder, a negative electrode conductive agent, and the like.

The negative electrode material includes, for example, a carbon material. The carbon material is graphitizable carbon, non-graphitizable carbon, graphite, low crystallinity carbon, or amorphous carbon. The shape of the carbon material is fibrous, spherical, granular, or scaly.

Further, the negative electrode material includes, for example, a metal-based material. Examples of metal-based materials include Li (lithium), Si (silicon), Sn (tin), Al (aluminum), Zr (zinc), and Ti (titanium). Metallic elements form compounds, mixtures, or alloys with other elements, such as silicon oxide (SiOx (0<x≦2)), silicon carbide (SiC), or alloys of carbon and silicon. Lithium titanate (LTO) is mentioned.

(Separator)
The separator 123 is a porous film containing resin, and may be a laminated film of two or more types of porous films. Resins include polypropylene and polyethylene. The separator 123 may include a porous membrane as a base layer and a resin layer on one or both sides thereof. This is because the adhesion of the separator 123 to each of the positive electrode 121 and the negative electrode 122 is improved, so that distortion of the electrode wound body 120 is suppressed.

The resin layer contains resin such as PVdF. When forming this resin layer, a solution in which a resin is dissolved in an organic solvent is applied to the base layer, and then the base layer is dried. In addition, after immersing the base material layer in the solution, the base material layer may be dried. It is preferable that the resin layer contains inorganic particles or organic particles from the viewpoint of improving heat resistance and battery safety. Types of inorganic particles include aluminum oxide, aluminum nitride, aluminum hydroxide, magnesium hydroxide, boehmite, talc, silica, and mica. Further, instead of the resin layer, a surface layer formed by a sputtering method, an ALD (atomic layer deposition) method, or the like and containing inorganic particles as a main component may be used.

(electrolyte)
The electrolytic solution contains a solvent and an electrolyte salt, and may further contain additives as necessary. The solvent is a non-aqueous solvent such as an organic solvent, or water. An electrolytic solution containing a nonaqueous solvent is called a nonaqueous electrolyte. Examples of the nonaqueous solvent include a cyclic carbonate, a chain carbonate, a lactone, a chain carboxylic acid ester, and a nitrile (mononitrile).

A typical example of the electrolyte salt is a lithium salt, but it may also contain salts other than lithium salts. Lithium salts include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), and trifluoromethanesulfonic acid. These include lithium (LiCF ₃ SO ₃ ), dilithium hexafluorosilicate (Li ₂ SF ₆ ), and the like. A mixture of these salts can be used, and among them, it is preferable to use a mixture of LiPF ₆ and LiBF ₄ from the viewpoint of improving battery characteristics.

(Effects obtained by this embodiment)
According to this embodiment described above, for example, the following effects can be obtained.
In the cylindrical battery as shown in the example of FIG. 10, the central region of the battery lid 114 is the positive electrode, and the caulking structure 111R is the negative electrode, and the positive electrode and the negative electrode are close to each other. If water droplets adhere from the negative electrode to the positive electrode across the area from the caulked structure to the center of the battery lid (referred to as the proximal area), electrolytic corrosion may occur. For this reason, there has been a particular demand for the waterproof function of a battery pack housing a cylindrical battery to prevent moisture from entering into the vicinity of the battery pack.
In this embodiment, the convex portion 22 of the metal plate 5 is arranged so as to face the bent portion (convex portion of the battery periphery) of the caulking structure 111R. Therefore, it is possible to prevent moisture from entering into the vicinity, and it is possible to realize the waterproof function of the battery pack.
According to this embodiment, by arranging the peripheral convex portion of the battery and the convex portion of the metal plate so as to face each other, the waterproof function of the battery pack is realized without using waterproof parts such as cushioning material or packing. can do.
Furthermore, since no waterproof parts are used, the assembly of each part can be simplified, and malfunctions due to poor assembly can be prevented. Furthermore, since no waterproof components are used, component costs can be reduced.
By positioning the convex portion of the metal plate using a jig and further welding the positive electrode side first, it is possible to suppress the occurrence of misalignment of the metal plate.

[2. Battery pack according to second embodiment]
In the example of the battery pack 1 of the first embodiment, the positive electrode terminal portion 15 is formed in a shape protruding from the center of one end surface of the battery cell 4, and the negative electrode terminal portion 16 is formed in a planar shape on the other end surface side of the battery cell 4. was being formed. The battery cell 4 housed in the battery pack 1 is not limited to this example, and a negative electrode terminal portion is formed in a shape protruding from the center of one end surface of the battery cell, and a positive electrode terminal portion is formed in a flat shape on the other end surface side of the battery cell. It may be formed in a shape. In the battery pack according to the second embodiment, the metal plate corresponding to the metal plate 5 is connected to the negative terminal of the battery cell, and the metal plate has a convex portion corresponding to the peripheral convex portion of the negative terminal. becomes.

[3. Application example]
In an application example, a power tool including the above-mentioned battery pack will be described.

Referring to FIG. 11, an example of an electric screwdriver as an electric tool to which the present invention is applicable will be schematically described. The electric driver 431 is provided with a motor 433 that transmits rotational power to a shaft 434 and a trigger switch 432 that is operated by a user. A battery pack 430 and a motor control unit 435 are housed in a lower housing of the handle of the electric screwdriver 431. The battery pack 430 is either built into the electric screwdriver 431 or is detachable. The battery pack according to the present invention can be used as the battery pack 430.

Each of the battery pack 430 and the motor control unit 435 may be equipped with a microcomputer (not shown), so that charging/discharging information of the battery pack 430 can be communicated with each other. The motor control unit 435 can control the operation of the motor 433 and cut off power supply to the motor 433 in the event of an abnormality such as overdischarge.

Power tools used outdoors are used in harsh conditions such as being exposed to wind and rain. Even if the battery pack is placed under such harsh conditions, the waterproofness of the battery pack is improved by maintaining the close contact between the protrusions on the metal plate and the protrusions on the peripheral edge of the battery.

[4. Modified example]
Although the embodiments and application examples of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and application examples, and various modifications based on the technical idea of the present invention are possible. It is.

For example, the configurations, methods, processes, shapes, materials, etc. mentioned in the above-mentioned embodiments and application examples are merely examples, and different configurations, methods, processes, shapes, materials, etc. may be used as necessary. good. Furthermore, the configurations, methods, processes, shapes, materials, etc. of the embodiments and examples described above can be combined with each other without departing from the spirit of the present invention.

1 Battery pack 2 Exterior case 2a Upper case 2b Lower case 4 Battery cell 5, 50 Metal plate 15 Positive terminal portion 16 Negative electrode terminal portion 18 Board connection terminal 23 First insulating portion 24 Outside slope portion 25 Inside slope portion 26 Convex portion Top part 27 Second insulating part 28 Slit 29 Thin part 31 Washer 430 Battery pack 431 Electric screwdriver

Claims (11)

exterior case,
A cylindrical battery cell having a positive terminal at one end and a negative terminal at the other end;
a metal plate connected to the positive terminal part or the negative terminal part,
The battery cell has a peripheral convex portion around the positive electrode terminal portion or the negative electrode terminal portion,
The metal plate has a convex portion facing the peripheral convex portion,
In the battery pack, the convex portion is disposed in close contact with the entire circumference of the peripheral convex portion via a first insulating portion. The battery pack according to claim 1, wherein a side surface of the battery cell and the peripheral convex portion are covered with the first insulating portion. The battery pack according to claim 1 or 2, wherein a slit is provided in a part of the outer periphery of the convex portion. The battery pack according to any one of claims 1 to 3, further comprising a second insulating part between the convex part and the first insulating part. The battery pack according to claim 4, wherein the second insulating portion is an insulating layer formed on at least a portion of the convex portion by painting or printing. The battery pack according to any one of claims 1 to 5, wherein a thin wall portion is provided inside the convex portion of the metal plate. The battery pack according to claim 6, wherein the thin portion is formed along the convex portion. The battery pack according to claim 6, wherein the thin portion has a cross shape. The battery pack according to any one of claims 1 to 8, wherein the convex portion and the peripheral convex portion are in contact with each other at an outer side of a protruding end of the peripheral convex portion. The battery pack according to any one of claims 1 to 9, wherein the convex portion has an inclined surface formed outward from a region where the metal plate faces the positive electrode terminal. A power tool comprising the battery pack according to any one of claims 1 to 10.

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